Para-xylene and para-diethylbenzene in C.sub.8 or C.sub.10 aromatic hydrocarbon mixtures are widely employed in the manufacture of synthetic fibers and also as industrial materials. The demand for para-xylene has been increasing in particular, and it relates to the demand for synthetic fibers.
Traditionally, para-xylene has been separated from C.sub.8 aromatic hydrocarbon mixtures by crystallization. Recently, a new method of separation, using an adsorbent, has been disclosed. Many different kinds of adsorbents have been proposed.